Biodiversity & Conservation

Penny weed - Zanardinia typus

Zanardinia typus

Image Ken Collins - Penny weed Zanardinia typus. Image width ca 8 cm.
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Distribution map

Zanardinia typus recorded (dark blue bullet) and expected (light blue bullet) distribution in Britain and Ireland (see below)

Why do the maps differ?

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Zanardinia typus is not listed under any importance categories.

Taxonomy icon Taxonomy Taxon English term
Phylum Ochrophyta Brown and yellow-green seaweeds
Class Phaeophyceae
Authority Nardo
Recent synonyms Zanardinia prototypus
Map icon Recorded Distribution in Britain and Ireland Found on southern and western coasts of England and the south and south western coasts of Ireland.
Habitat information icon Habitat information Found mainly on silty boulders or bedrock, rarely on living substrata, sublittorally from shallow water to about 20 m depth.
Text page icon Description Zanardinia typus is a fairly small brown seaweed with flat fronds that may be either round or fan-like and possibly irregular in shape. The appearance may change with age, varying in colour from olive to dark brown or black and in texture from smooth to leathery. The edge of the fronds may be smooth or ruffled, and has a distinct fringe of hairs.
Identifying features
  • Horizontal, flat fronds that may be round or fan-like.
  • Up to 20 cm across.
  • Margin of the fronds with a fringe of short hairs, 3-4 mm long.
  • Colour varies from olive to dark brown or black.
  • Texture varies from smooth to leathery.
  • Loosely attached to the substratum by rhizoids on the undersurface.
Additional information icon Additional information The above taxonomy uses the recent species name given by Hardy & Guiry (2003). Howson & Picton (1997) used the name Zanardinia prototypus.

Until 1973 the most northern record of Zanardinia prototypus was in the Channel Islands where it was considered rare. It was first recorded in Britain in 1973 at a site in south Devon (Jephson et al, 1975). In 1982 it was reported at sites on the coasts of Cornwall, Devon, Lundy, Pembrokeshire, and southwest Ireland although no reproductive structures were seen (Hiscock & Maggs, 1982) but it has been rarely seen since (Keith Hiscock, pers comm.).

This review can be cited as follows:

Penny Avant 2006. Zanardinia typus. Penny weed. Marine Life Information Network: Biology and Sensitivity Key Information Sub-programme [on-line]. Plymouth: Marine Biological Association of the United Kingdom. [cited 03/09/2010]. Available from: <http://www.marlin.ac.uk/speciesinformation.php?speciesID=4589>